KR102444741B1 - Method for manufacturing non-woven fabric for water-treatment membrane support and non-woven fabric for water-treatment membrane support manufactured thereby - Google Patents

Abstract

The present specification includes the steps of preparing a dispersion by mixing a main fiber, a binder fiber and a dispersion medium; removing the dispersion medium from the dispersion to prepare a wet nonwoven fabric; and drying the wet nonwoven fabric and then heat-compressing it, wherein the binder fiber includes a low melting point polymer resin and polymer pulp, and the melting point of the binder fiber is lower than the melting point of the main fiber. It relates to a method for manufacturing a nonwoven fabric for a support and to a nonwoven fabric for a support for a water treatment separation membrane produced thereby.

Description

Method for manufacturing a non-woven fabric for a water treatment membrane support and a non-woven fabric for a water treatment membrane support manufactured thereby

The present specification relates to a method for manufacturing a nonwoven fabric for a water treatment separation membrane support and to a nonwoven fabric for a water treatment separation membrane support manufactured thereby.

Osmosis is a phenomenon in which the solvent moves through the separation membrane from a solution with a low solute concentration to a solution with a high solute concentration between two solutions separated by a semipermeable membrane. The pressure is called osmotic pressure. However, if an external pressure higher than the osmotic pressure is applied, the solvent moves toward the solution with a low solute concentration, which is called reverse osmosis. Using the reverse osmosis principle, it is possible to separate various salts or organic substances through a semipermeable membrane by using a pressure gradient as a driving force. The water treatment membrane using this reverse osmosis phenomenon is used to supply water for home, construction, and industrial use by separating substances at the molecular level and removing salts from brine or seawater.

A typical example of such a water treatment separation membrane is a polyamide-based water treatment separation membrane. The polyamide-based water treatment separation membrane is manufactured by forming a polyamide active layer on a microporous support.

A nonwoven fabric is generally used as the support, and research on improving the performance of a water treatment separation membrane by controlling the pore characteristics of the nonwoven fabric is an important situation.

Korean Patent Registration Publication No. 10-1526080

The present specification provides a method for manufacturing a nonwoven fabric for a water treatment separation membrane support, a nonwoven fabric for a water treatment separation membrane support manufactured thereby, a water treatment separation membrane including the nonwoven fabric for the water treatment separation membrane support, and a water treatment module including the water treatment separation membrane.

An exemplary embodiment of the present specification is

mixing the main fiber, the binder fiber and the dispersion medium to prepare a dispersion;

removing the dispersion medium from the dispersion to prepare a wet nonwoven fabric; and

After drying the wet nonwoven fabric, it comprises the step of heat-pressing,

The binder fiber is to include a low-melting polymer resin and polymer pulp,

The melting point of the binder fiber provides a method of manufacturing a nonwoven fabric for a water treatment membrane support that is lower than the melting point of the main fiber.

In addition, an exemplary embodiment of the present specification provides a nonwoven fabric for a water treatment separation membrane support manufactured according to the manufacturing method of the nonwoven fabric for a water treatment separation membrane support.

In addition, an exemplary embodiment of the present specification provides a water treatment separation membrane including the nonwoven fabric for the water treatment separation membrane support.

In addition, an exemplary embodiment of the present specification provides a water treatment module including one or more of the water treatment separation membrane.

The method for manufacturing a nonwoven fabric for a water treatment membrane support according to an exemplary embodiment of the present specification has the advantage of being able to manufacture a nonwoven fabric for a water treatment membrane support having excellent air permeability by mixing a low melting point polymer resin and polymer pulp and using it as a binder.

1 is an image of the surface of the nonwoven fabric prepared in Example 1 and Comparative Example 1 of the present specification observed with a scanning electron microscope (SEM).

Hereinafter, the present specification will be described in more detail.

In the present specification, when a member is said to be positioned 'on' another member, this includes not only a case in which a member is in contact with another member but also a case in which another member exists between the two members.

In the present specification, when a part 'includes' a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

As used herein, a 'polymer' has a weight average molecular weight of 500 g/mol or more and 5,000,000 g/mol or less.

As used herein, the term 'fiber' refers to a material in which a thermoplastic polymer such as polyethylene terphthalate homopolymer or copolymer, polyethylene, etc. is fibrous, for example, a material having a diameter of several nm to several tens of μm and a length significantly longer than the diameter. do.

In the present specification, 'pulp' is a fiber manufactured to have a shape similar to wood pulp by fibrillating a fiber made of a synthetic polymer through a method such as pulverization, and the average diameter of the fiber is 0.001 mm to 0.1 mm, The average length means 0.1 mm to 2.0 mm.

An exemplary embodiment of the present specification comprises the steps of preparing a dispersion by mixing a main fiber, a binder fiber, and a dispersion medium; removing the dispersion medium from the dispersion to prepare a wet nonwoven fabric; and drying the wet nonwoven fabric and then heat-compressing it, wherein the binder fiber includes a low melting point polymer resin and polymer pulp, and the melting point of the binder fiber is lower than the melting point of the main fiber. A method for producing a nonwoven fabric for a support is provided.

Conventionally, a low-melting-point polyester or undrawn polyester yarn was used as a binder fiber for manufacturing a nonwoven fabric for a water treatment membrane support. However, in the case of low-melting polyester or polyester undrawn yarn, there is a limit in controlling the pore properties, since it is common that the fineness is 1.0 denier or more due to manufacturing difficulties.

Accordingly, the present inventors prepared a nonwoven fabric with improved air permeability and uniformity without a decrease in tensile strength by mixing a low melting point polymer resin and polymer pulp and using it as a binder. This is because the polymer pulp has a fine fibril structure and thus the average fiber diameter is reduced, so that the average pores of the nonwoven fabric using the same can be reduced and the uniformity can be improved.

In particular, the low melting point polymer resin and the polymer pulp contained in the binder fiber used a lower melting point than the main fiber, which is not melted in the heat compression step and remains in the shape of the fiber and cannot serve as a binder. in order to prevent In addition, in this case, since the shape of the fiber remains as it is and may interfere with the characteristics of the main fiber originally intended to be obtained, this is to prevent this.

As used herein, the term 'main fiber' refers to a fiber included in excess of 50 wt% based on 100 wt% of the fiber included in the dispersion.

As used herein, the term 'binder fiber' refers to a fiber that can serve as a binder, and when heated, softening or melting occurs to create a bond between the fibers constituting the nonwoven fabric.

In one embodiment of the present specification, the main fiber may be at least one selected from polyester fiber, polyamide fiber, polyphenylene sulfide fiber, polypropylene fiber, and polyvinyl alcohol fiber, preferably It may be polyester fiber. Polyester fibers have advantages of excellent liquid permeability, tensile strength, wet strength and durability, and low price.

In the exemplary embodiment of the present specification, the dispersion medium is not particularly limited as long as it is a material capable of dispersing the main fiber and the binder fiber, but preferably water.

In an exemplary embodiment of the present specification, the step of mixing the main fiber, the binder fiber and the dispersion medium may be performed through stirring, and the stirring may be performed at 500 rpm to 3,000 rpm for 1 minute to 30 minutes.

In one embodiment of the present specification, the low melting point polymer resin may be at least one selected from low melting point polyester, unstretched polyester, polypropylene and polyethylene, and preferably low melting point polyester. The low-melting-point polyester has excellent binding properties even at low temperatures, and excellent tensile strength and chemical resistance.

In one embodiment of the present specification, the low-melting polymer resin may be selected to include the same type of polymer as the main fiber. For example, when the main fiber is a polyester fiber, the low melting point polymer resin may be a low melting point polyester.

In an exemplary embodiment of the present specification, the melting point or softening point of the low-melting polymer resin may be 200° C. or less, preferably 190° C. or less, and more preferably 150° C. or less. When the melting point or softening point of the low melting point polymer resin is 200° C. or less, it is possible to prevent the problem that the low melting point polymer resin does not melt during the heat compression process and thus does not function as a binder.

In one embodiment of the present specification, the polymer pulp may be one or more selected from polyethylene pulp, polypropylene pulp, and low-melting polyester pulp, and preferably polyethylene pulp. Polyethylene pulp has advantages of excellent chemical resistance and low melting point.

In one embodiment of the present specification, the polymer pulp has an average diameter of fibers of 0.001 mm to 0.1 mm, preferably 0.01 mm to 0.05 mm, and an average length of fibers of 0.1 mm to 2.0 mm, preferably 0.5 mm to 1.5 mm.

In an exemplary embodiment of the present specification, the melting point of the polymer pulp may be 200 ℃ or less, preferably 190 ℃ or less, more preferably 150 ℃ or less. When the melting point of the polymer pulp is 200° C. or less, it is possible to prevent the problem that the polymer pulp does not melt in the heat-pressing process and thus does not serve as a binder.

In one embodiment of the present specification, the content of the polymer pulp is 5 wt% to 45 wt%, preferably 10 wt% to 35 wt%, more preferably 15 wt% to 25 wt% based on 100 wt% of the binder fiber. .

When the content of the polymer pulp is 5 wt% or more, the pore properties obtained by using the polymer in the form of pulp can be sufficiently secured, and when the content of the polymer pulp is less than 45 wt%, the problem that the air permeability is lowered due to too fine pores can be prevented.

In the exemplary embodiment of the present specification, the wet nonwoven fabric includes the main fiber and the binder fiber in a weight ratio of 95:5 to 55:45, preferably 85:15 to 55:45, more preferably It is included in a weight ratio of 70:30 to 55:45.

When the weight ratio of the main fiber and the binder fiber is in the above range, the tensile strength, the average pore size, etc. have a suitable range for use as a nonwoven fabric for a water treatment membrane. Specifically, when the binder fiber is included in 5 wt% or more based on 100 wt% of the main fiber and the binder fiber, the surface can be uniformly formed while the nonwoven fabric has sufficient strength, and when it is included in 45 wt% or less, air permeability at a low cost can be improved

In an exemplary embodiment of the present specification, in the wet nonwoven fabric, the low melting point polymer resin and the polymer pulp are included in a weight ratio of 95:5 to 55:45, preferably 90:10 to 60:40, more preferably Preferably, it is included in a weight ratio of 90:10 to 70:30.

When the weight ratio of the low-melting polymer resin and the polymer pulp is within the above range, the tensile strength, the average pore size, etc. have a suitable range for use as a nonwoven fabric for a water treatment separation membrane.

In an exemplary embodiment of the present specification, the drying of the wet-laid nonwoven fabric may be performed in an oven at 80° C. to 150° C. for 1 minute to 30 minutes.

In an exemplary embodiment of the present specification, the heat compression bonding may be performed by calendering at a temperature of 100°C to 200°C, specifically, after primary calendering at a temperature of 100°C to 180°C, 120 It may be carried out by a method of secondary calendering at a temperature of ℃ to 200 ℃. When the temperature of the secondary calendering is higher than that of the primary, re-melting of the low-density defects proceeds, thereby reducing the occurrence of the low-density defects, thereby increasing the uniformity and smoothness.

An exemplary embodiment of the present specification provides a nonwoven fabric for a water treatment membrane support manufactured according to the method for manufacturing a nonwoven fabric for a water treatment membrane support described above.

In an exemplary embodiment of the present specification, the nonwoven fabric may have air permeability of 0.5 cc/cm ² /s or more.

The air permeability is measured by using an air permeability tester (FX-3300, Textest Co.) according to ASTM D737 (Air permeability at 125Pa) standard, the air permeability of a 20 cm × 20 cm sample.

In an exemplary embodiment of the present specification, the tensile strength of the nonwoven fabric for the water treatment separation membrane support is 80N/15mm or more, preferably 85N/15mm or more, and more preferably 90N/15mm or more.

In one embodiment of the present specification, the average pore size of the nonwoven fabric for the water treatment separation membrane support is 7 μm or less, preferably 5 μm or less. When the average pore size is 7 μm or less, the uniformity of the pore size is high, so that the physical strength is improved, and there is an advantage in that the polymer and other materials do not leak when the nonwoven fabric is coated. In addition, there is an advantage that the coating aptitude can be improved when the semipermeable membrane coating solution is mounted on the nonwoven fabric used as the substrate.

In an exemplary embodiment of the present specification, the thickness of the nonwoven fabric for the water treatment separation membrane support is 100 μm or less. When the thickness of the nonwoven fabric is 100 μm or less, it is possible to manufacture a miniaturized water treatment module, and there is an advantage that a thicker separator can be introduced.

An exemplary embodiment of the present specification provides a water treatment separation membrane comprising the nonwoven fabric for the above-described water treatment separation membrane support.

In an exemplary embodiment of the present specification, the water treatment membrane is prepared by coating a polymer material on the nonwoven fabric for the water treatment membrane support to prepare a porous support; and interfacial polymerization of an amine compound and an acyl halide compound to form a polyamide active layer on the porous support.

In one embodiment of the present specification, the polymer material is polysulfone, polyethersulfone, polycarbonate, polyethylene oxide, polyimide, polyetherimide, polyetheretherketone, polypropylene, polymethylpentene, polymethylchloride or poly It may be vinylidene fluoride, preferably polysulfone.

In an exemplary embodiment of the present specification, the forming of the polyamide active layer includes: forming an aqueous solution layer including an amine compound on the porous support; and contacting an organic solution containing an acyl halide compound and an organic solvent on the aqueous solution layer containing the amine compound.

When the aqueous solution layer containing the amine compound is in contact with the organic solution, the amine compound and the acyl halide compound coated on the surface of the porous support react to generate polyamide by interfacial polymerization, and are adsorbed to the microporous support to form a thin film this is formed The contact method may use a method such as dipping, spraying or coating.

In an exemplary embodiment of the present specification, the amine compound is not limited as long as it can be used for polymerization of polyamide, but m-phenylenediamine (mPD), p-phenylenediamine (PPD), 1,3,6- benzenetriamine (TAB), 4-chloro-1,3-phenylenediamine, 6-chloro-1,3-phenylenediamine, 3-chloro-1,4-phenylenediamine, or a mixture thereof, Preferably, it may be m-phenylenediamine (mPD).

In an exemplary embodiment of the present specification, the content of the amine compound may be 0.1wt% to 10wt% based on 100wt% of the aqueous solution containing the amine compound, preferably 1wt% to 9wt%, more preferably It may be 2 wt% to 8 wt%.

When the content of the amine compound is within the above range, it is possible to prepare a uniform polyamide active layer.

In one embodiment of the present specification, the aqueous solution containing the amine compound may further include a surfactant.

In one embodiment of the present specification, the surfactant may be selected from nonionic, cationic, anionic and amphoteric surfactants. According to an exemplary embodiment of the present specification, the surfactant is sodium lauryl sulfate (SLS); alkyl ether sulfates; alkyl sulfates; olefin sulfonates; alkyl ether carboxylates; sulfosuccinates; aromatic sulfonates; octylphenol ethoxylates; ethoxylated nonylphenols; alkyl poly(ethylene oxide); copolymers of poly(ethylene oxide) and poly(propylene oxide); alkyl polyglucosides such as octyl glucoside and decyl maltoside; fatty acid alcohols such as cetyl alcohol, oleyl alcohol, cocamide MEA, cocamide DEA, alkyl hydroxyethyl dimethyl ammonium chloride, cetyltrimethyl ammonium bromide, cetyltrimethyl ammonium chloride, hexadecyltrimethylammonium bromide and hexadecyltrimethylammonium chloride; and alkyl betaines. Specifically, the surfactant may be SLS, octylphenol ethoxylates, or ethoxylated nonylphenols.

In particular, when sodium lauryl sulfate (SLS) is used as the surfactant, SLS has a high affinity for water and oil (Hydrophile-Lipophile Balance, HLB), so it is easily soluble in water and has a Critical Michelle Concentration. , CMC) is also high, so even if it is added in an excessive amount, the formation of the polyamide active layer is not inhibited.

In one embodiment of the present specification, the surfactant may be 0.005 wt% to 10 wt% based on 100 wt% of the aqueous solution containing the amine compound.

In an exemplary embodiment of the present specification, a method of forming an aqueous solution layer including an amine compound on the porous support is not particularly limited, and any method capable of forming an aqueous solution layer on the support may be used without limitation. Specifically, the method of forming the aqueous solution layer containing the amine compound on the porous support may include spraying, application, immersion or dripping.

In one embodiment of the present specification, the aqueous solution layer may be additionally subjected to a step of removing the aqueous solution containing the excess amine compound, if necessary. The aqueous solution layer formed on the porous support may be non-uniformly distributed when the aqueous solution present on the support is too large. When the aqueous solution is non-uniformly distributed, a non-uniform polyamide active layer may be formed by subsequent interfacial polymerization. . Therefore, it is preferable to remove the excess aqueous solution after forming the aqueous solution layer on the support. The excess aqueous solution removal is not particularly limited, but may be performed using, for example, a sponge, an air knife, nitrogen gas blowing, natural drying, or a compression roll.

The acyl halide compound is not limited as long as it can be used for polymerization of polyamide, but an aromatic compound having 2 to 3 carboxylic acid halides, for example, trimesoyl chloride, isophthaloyl chloride and terephthaloyl One or a mixture of two or more selected from the group of compounds consisting of chloride may be preferably used, preferably trimesoyl chloride may be used.

In one embodiment of the present specification, it is preferable that the organic solvent does not participate in the interfacial polymerization reaction, and an aliphatic hydrocarbon solvent, for example, isoparaffinic, which is a mixture of freons and alkanes having 5 to 12 carbon atoms and alkanes. It may include one or more selected from solvents. Specifically, hexane, heptane, octane, nonane, decane, undecane, dodecane, cyclohexane, IsoPar (Exxon), IsoPar G (Exxon), ISOL-C (SK Chem) and ISOL-G (Exxon) may be used. However, it is not limited thereto.

The content of the acyl halide compound may be 0.05wt% to 1wt%, preferably 0.1wt% to 0.7wt%, more preferably 0.2wt% to 0.5wt% based on 100wt% of the organic solution.

When the content of the acyl halide compound is in the above range, it is possible to prepare a uniform polyamide active layer.

The water treatment separation membrane may be manufactured using materials and methods known in the art, except for using the nonwoven fabric for the water treatment separation membrane support as a support.

In an exemplary embodiment of the present specification, the water treatment separation membrane may be a micro filtration membrane, an ultra filtration membrane, a nano filtration membrane, or a reverse osmosis membrane, specifically, a reverse osmosis membrane. .

One embodiment of the present invention provides a water treatment module including at least one or more of the above-described water treatment separation membrane.

The specific type of the water treatment module is not particularly limited, and examples thereof include a plate & frame module, a tubular module, a hollow & fiber module, or a spiral wound module. In addition, as long as the water treatment module includes the reverse osmosis membrane according to the exemplary embodiment of the present specification, other configurations and manufacturing methods are not particularly limited, and general means known in this field may be employed without limitation. .

On the other hand, since the water treatment module according to an exemplary embodiment of the present specification has excellent salt removal rate and boron removal rate, it can be usefully used in water treatment devices such as household/industrial water purification devices, sewage treatment devices, sea desalination devices, and the like.

Hereinafter, examples will be given to describe the present specification in detail. However, the embodiments according to the present specification may be modified in various other forms, and the scope of the present specification is not to be construed as being limited to the embodiments described below. The embodiments of the present specification are provided to more completely explain the present specification to those of ordinary skill in the art.

<Example: Preparation of non-woven fabric>

Example 1.

Polyester (PET) fiber (manufacturer: Woongjin Chemical, melting point 250℃) with a fineness of 0.7 denier and an average length of 5 mm as the main fiber, and a low-melting polyester with a fineness of 2.0 denier and an average length of 6 mm as a binder fiber ( LM-PET) (manufacturer: Huvis, melting point 110℃) and polyethylene (PE) pulp with an average fiber length of 0.9mm and a fiber diameter of 15㎛ (manufacturer: Minifibers, melting point 135℃) were used, and the main fiber and Based on 100wt% of binder fiber, PET was 60wt%, LM-PET was 32wt%, and PE pulp was 8wt%. A mixed dispersion was prepared by putting the main fiber and the binder fiber in water as a dispersion medium, and vigorously stirring for 10 minutes at room temperature with a stirrer (pulper). After transferring the mixed dispersion to a wet non-woven fabric maker, water as a dispersion medium is removed using a screen mesh so that the weight ratio of PET fiber and binder fiber is 60:40, and the weight ratio of LM-PET and PE pulp, which is the binder fiber, is An 80:20 wet-laid nonwoven fabric was prepared. After drying at 110°C, calendering was performed at 120°C using a roll calender, and then calendered at 140°C secondly to prepare a nonwoven fabric of 75 g/m ² .

Comparative Example 1.

A nonwoven fabric was prepared in the same manner as in Example 1, except that in Example 1, only 40 wt% of LM-PET without PE pulp was used as the binder fiber.

Comparative Example 2.

A nonwoven fabric was prepared in the same manner as in Example 1, except that in Example 1, only 40 wt% of PE pulp was used without LM-PET as the binder fiber.

<Experimental example: performance evaluation of nonwoven fabric>

For performance evaluation of the nonwoven fabrics prepared according to Examples and Comparative Examples, thickness, air permeability, tensile strength, and average pore size were measured and described in Table 1. For air permeability, the air permeability of a sample of 20 cm × 20 cm was measured using an air permeability tester (FX-3300, Textest) in accordance with ASTM D737 (Air permeability at 125 Pa) standard. is 15 mm, the longitudinal direction (MD) and the transverse direction (CD) are respectively measured under the conditions of a gripping length of 50 mm and a tensile speed of 50 mm/min.

thickness
(μm) breathability
(cc/cm ² /s) MD tensile strength
(N/15mm) CD tensile strength
(N/15mm) average pore size
(μm) Example 1 83.5±1.3 0.59±0.09 95.8±1.3 95.3±0.5 4.9 Comparative Example 1 85.0±1.8 0.45±0.26 95.6±0.9 95.9±0.8 5.1 Comparative Example 2 88.9±4.2 0.07±0.01 44.3±3.0 36.1±1.2 6.4

From the results of Table 1, it can be confirmed that, in the case of Example 1, an improved air permeability could be obtained without deterioration of other properties such as thickness, tensile strength, and pore size compared to Comparative Example 1. In addition, in the case of Comparative Example 2 using only PE pulp, it was confirmed that the tensile strength and air permeability were significantly reduced. When the air permeability is high, there is an advantage in that a high filtration flow rate can be obtained when applied to a water treatment membrane.

In addition, referring to FIG. 1 , it can be seen that the nonwoven fabric manufactured in Comparative Example 1 has a shape having a poor surface uniformity, whereas the nonwoven fabric manufactured in Example 1 has a relatively uniform shape. Through this, it can be confirmed that the nonwoven fabric manufactured according to the present invention has an advantage of excellent uniformity.

Claims (12)

mixing the main fiber, the binder fiber and the dispersion medium to prepare a dispersion;
removing the dispersion medium from the dispersion to prepare a wet nonwoven fabric; and
After drying the wet nonwoven fabric, it comprises the step of heat-pressing,
The binder fiber is to include a low-melting polymer resin and polymer pulp,
The melting point or softening point of the low-melting polymer resin is 150° C. or less,
The melting point of the binder fiber is a method of manufacturing a nonwoven fabric for a water treatment membrane support that is lower than the melting point of the main fiber. The method according to claim 1,
The content of the polymer pulp is 5 wt% to 45 wt% based on 100 wt% of the binder fiber Method for producing a nonwoven fabric for a water treatment membrane support. The method according to claim 1,
The wet nonwoven fabric comprises the main fiber and the binder fiber in a weight ratio of 95:5 to 55:45. The method according to claim 1,
The method for producing a nonwoven fabric for a water treatment separation membrane support, wherein the wet nonwoven fabric comprises the low melting point polymer resin and the polymer pulp in a weight ratio of 95:5 to 55:45. delete The method according to claim 1,
The melting point of the polymer pulp is a method of manufacturing a nonwoven fabric for a water treatment membrane support that is 200 ℃ or less. The method according to claim 1,
The method for producing a nonwoven fabric for a water treatment membrane support, wherein the polymer pulp has an average diameter of fibers of 0.001 mm to 0.1 mm. The method according to claim 1,
The polymer pulp is a method for producing a nonwoven fabric for a water treatment membrane support that the average length of the fibers is 0.1mm to 2.0mm. A nonwoven fabric for a water treatment separation membrane support manufactured according to the method of any one of claims 1 to 4 and 6 to 8. 10. The method of claim 9,
Non-woven fabric for water treatment membrane support with air permeability of 0.5 cc/cm ² /s or more. A water treatment separation membrane comprising the nonwoven fabric for a water treatment separation membrane support according to claim 9 . A water treatment module comprising at least one water treatment separation membrane according to claim 11 .

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